With the trend of globalization these days, there is an increasing need for a speech translation device that supports communications between users who speak different languages. In fact, some services of providing speech translation functions have been operated. However, it is difficult to provide speech recognition or machine translation without errors. There is a method for prompting a speaker of a target language to point out incomprehensible translation so that a speaker of a source language can correct the translation or modify what they have said for better understanding.